Unknown,Transcriptomics,Genomics,Proteomics

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Novel strategies to enforce an epithelial phenotype in mesenchymal cells

ABSTRACT: E-cadherin downregulation in cancer cells is associated with epithelial-to-mesenchymal transition (EMT) and metastatic prowess, but the underlying mechanisms are incompletely characterized. In this study, we probed E-cadherin expression at the plasma membrane as a functional assay to identify genes involved in E-cadherin downregulation. The assay was based on the E-cadherin-dependent invasion properties of the intracellular pathogen Listeria monocytogenes. On the basis of a functional readout, automated microscopy and computer-assisted image analysis were used to screen siRNAs targeting 7,000 human genes. The validity of the screen was supported by its definion of several known regulators of E-cadherin expression, including ZEB1, HDAC1 and MMP14. We identified three new regulators (FLASH, CASP7 and PCGF1), the silencing of which was sufficient to restore high levels of E-cadherin transcription. Additionally, we identified two new regulators (FBXL5 and CAV2), the silencing of which was sufficient to increase E-cadherin expression at a post-transcriptional level. FLASH silencing regulated the expression of E-cadherin and other ZEB1-dependent genes, through post-transcriptional regulation of ZEB1, but it also regulated the expression of numerous ZEB1-independent genes with functions predicted to contribute to a restoration of the epithelial phenotype. Finally, we also report the identification of siRNA duplexes that potently restored the epithelial phenotype by mimicking the activity of known and putative microRNAs. Our findings suggest new ways to enforce epithelial phenotypes as a general strategy to treat cancer by blocking invasive and metastatic phenotypes associated with EMT The experiment is designed to compare gene expression in a mock treated HeLa229 cells versus FLASH-depleted and ZEB1-depleted cells in order to asses the specific role of ZEB1 and FLASH in epithelial-to- mezenchymal transition.

ORGANISM(S): Homo sapiens

SUBMITTER: Beile Gao

PROVIDER: E-GEOD-57660 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Metastatic colonization involves cancer cell lodgment or adherence in the microvasculature and subsequent migration of those cells across the endothelium into a secondary organ site. To study this process further, we analyzed transendothelial migration of human PC-3 prostate cancer cells in vitro. We isolated a subpopulation of cells, TEM4-18, that crossed an endothelial barrier more efficiently, but surprisingly, were less invasive than parental PC-3 cells in other contexts in vitro. Importantly, TEM4-18 cells were more aggressive than PC-3 cells in a murine metastatic colonization model. Microarray and FACS analysis of these cells showed that the expression of many genes previously associated with leukocyte trafficking and cancer cell extravasation were either unchanged or down-regulated. TEM4-18 cells exhibited characteristic molecular markers of an epithelial-to-mesenchymal transition (EMT), including frank loss of E-cadherin expression and upregulation of the E-cadherin repressor ZEB1. Silencing ZEB1 in TEM4-18 cells resulted in increased E-cadherin and reduced transendothelial migration. TEM4-18 cells also express N-cadherin, which was found to be necessary, but not sufficient for increased transendothelial migration. Our results extend the role of EMT in metastasis to transendothelial migration and implicate ZEB1 and N-cadherin in this process in prostate cancer cells. Experiment Overall Design: We wanted to compare the expression profiles of cells that had undergone transendothelial migration. The parental, and reference cell line, PC-3 was plated onto a confluent human microvascular endothelial cell line from the lung and allowed to migrate across this monolayer. A new cell line, TEM4-18, was isolated from this experiment. We also performed this experiment a second time to isolate a biological replicate of the TEM4-18 cell line, termed TEM2-5. All 3 cell lines, PC-3, TEM4-18, and TEM2-5 are analyzed as replicates in this experiment for a total of 6 samples in this microarray. Both TEM4-18 and TEM2-5 were then compared to PC-3 cells for changes in gene expression.

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Novel strategies to enforce an epithelial phenotype in mesenchymal cells

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